<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>使用For...In声明来遍历数组内的元素</title>
</head>

<body>
    <p>点击下面的按钮，循环遍历对象 "person" 的属性。</p>
    <button onclick="myFunction()">点击这里</button>
    <p id="demo"></p>
    <script>
        function myFunction() {
            var x;
            var txt = "";
            var person = { fname: "Bill", lname: "Gates", age: 56 };
            for (x in person) {
                txt = txt + person[x];
            }
            document.getElementById("demo").innerHTML = txt;
        }
    </script>
</body>

</html>